// Copyright 2007, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Author: wan@google.com (Zhanyong Wan)

// Google Test - The Google C++ Testing Framework
//
// This file implements a universal value printer that can print a
// value of any type T:
//
//   void ::testing::internal::UniversalPrinter<T>::Print(value, ostream_ptr);
//
// A user can teach this function how to print a class type T by
// defining either operator<<() or PrintTo() in the namespace that
// defines T.  More specifically, the FIRST defined function in the
// following list will be used (assuming T is defined in namespace
// foo):
//
//   1. foo::PrintTo(const T&, ostream*)
//   2. operator<<(ostream&, const T&) defined in either foo or the
//      global namespace.
//
// If none of the above is defined, it will print the debug string of
// the value if it is a protocol buffer, or print the raw bytes in the
// value otherwise.
//
// To aid debugging: when T is a reference type, the address of the
// value is also printed; when T is a (const) char pointer, both the
// pointer value and the NUL-terminated string it points to are
// printed.
//
// We also provide some convenient wrappers:
//
//   // Prints a value to a string.  For a (const or not) char
//   // pointer, the NUL-terminated string (but not the pointer) is
//   // printed.
//   std::string ::testing::PrintToString(const T& value);
//
//   // Prints a value tersely: for a reference type, the referenced
//   // value (but not the address) is printed; for a (const or not) char
//   // pointer, the NUL-terminated string (but not the pointer) is
//   // printed.
//   void ::testing::internal::UniversalTersePrint(const T& value, ostream*);
//
//   // Prints value using the type inferred by the compiler.  The difference
//   // from UniversalTersePrint() is that this function prints both the
//   // pointer and the NUL-terminated string for a (const or not) char pointer.
//   void ::testing::internal::UniversalPrint(const T& value, ostream*);
//
//   // Prints the fields of a tuple tersely to a string vector, one
//   // element for each field. Tuple support must be enabled in
//   // gtest-port.h.
//   std::vector<string> UniversalTersePrintTupleFieldsToStrings(
//       const Tuple& value);
//
// Known limitation:
//
// The print primitives print the elements of an STL-style container
// using the compiler-inferred type of *iter where iter is a
// const_iterator of the container.  When const_iterator is an input
// iterator but not a forward iterator, this inferred type may not
// match value_type, and the print output may be incorrect.  In
// practice, this is rarely a problem as for most containers
// const_iterator is a forward iterator.  We'll fix this if there's an
// actual need for it.  Note that this fix cannot rely on value_type
// being defined as many user-defined container types don't have
// value_type.

#ifndef GTEST_INCLUDE_GTEST_GTEST_PRINTERS_H_
#define GTEST_INCLUDE_GTEST_GTEST_PRINTERS_H_

#include <ostream>  // NOLINT
#include <sstream>
#include <string>
#include <utility>
#include <vector>
#include "gtest/internal/gtest-port.h"
#include "gtest/internal/gtest-internal.h"

namespace testing
{

	// Definitions in the 'internal' and 'internal2' name spaces are
	// subject to change without notice.  DO NOT USE THEM IN USER CODE!
	namespace internal2
	{

		// Prints the given number of bytes in the given object to the given
		// ostream.
		GTEST_API_ void PrintBytesInObjectTo(const unsigned char *obj_bytes,
		                                     size_t count,
		                                     ::std::ostream *os);

		// For selecting which printer to use when a given type has neither <<
		// nor PrintTo().
		enum TypeKind
		{
			kProtobuf,              // a protobuf type
			kConvertibleToInteger,  // a type implicitly convertible to BiggestInt
			// (e.g. a named or unnamed enum type)
			kOtherType              // anything else
		};

		// TypeWithoutFormatter<T, kTypeKind>::PrintValue(value, os) is called
		// by the universal printer to print a value of type T when neither
		// operator<< nor PrintTo() is defined for T, where kTypeKind is the
		// "kind" of T as defined by enum TypeKind.
		template <typename T, TypeKind kTypeKind>
		class TypeWithoutFormatter
		{
		public:
			// This default version is called when kTypeKind is kOtherType.
			static void PrintValue(const T &value, ::std::ostream *os)
			{
				PrintBytesInObjectTo(reinterpret_cast<const unsigned char *>(&value),
				                     sizeof(value), os);
			}
		};

		// We print a protobuf using its ShortDebugString() when the string
		// doesn't exceed this many characters; otherwise we print it using
		// DebugString() for better readability.
		const size_t kProtobufOneLinerMaxLength = 50;

		template <typename T>
		class TypeWithoutFormatter<T, kProtobuf>
		{
		public:
			static void PrintValue(const T &value, ::std::ostream *os)
			{
				const ::testing::internal::string short_str = value.ShortDebugString();
				const ::testing::internal::string pretty_str =
				    short_str.length() <= kProtobufOneLinerMaxLength ?
				    short_str : ("\n" + value.DebugString());
				*os << ("<" + pretty_str + ">");
			}
		};

		template <typename T>
		class TypeWithoutFormatter<T, kConvertibleToInteger>
		{
		public:
			// Since T has no << operator or PrintTo() but can be implicitly
			// converted to BiggestInt, we print it as a BiggestInt.
			//
			// Most likely T is an enum type (either named or unnamed), in which
			// case printing it as an integer is the desired behavior.  In case
			// T is not an enum, printing it as an integer is the best we can do
			// given that it has no user-defined printer.
			static void PrintValue(const T &value, ::std::ostream *os)
			{
				const internal::BiggestInt kBigInt = value;
				*os << kBigInt;
			}
		};

		// Prints the given value to the given ostream.  If the value is a
		// protocol message, its debug string is printed; if it's an enum or
		// of a type implicitly convertible to BiggestInt, it's printed as an
		// integer; otherwise the bytes in the value are printed.  This is
		// what UniversalPrinter<T>::Print() does when it knows nothing about
		// type T and T has neither << operator nor PrintTo().
		//
		// A user can override this behavior for a class type Foo by defining
		// a << operator in the namespace where Foo is defined.
		//
		// We put this operator in namespace 'internal2' instead of 'internal'
		// to simplify the implementation, as much code in 'internal' needs to
		// use << in STL, which would conflict with our own << were it defined
		// in 'internal'.
		//
		// Note that this operator<< takes a generic std::basic_ostream<Char,
		// CharTraits> type instead of the more restricted std::ostream.  If
		// we define it to take an std::ostream instead, we'll get an
		// "ambiguous overloads" compiler error when trying to print a type
		// Foo that supports streaming to std::basic_ostream<Char,
		// CharTraits>, as the compiler cannot tell whether
		// operator<<(std::ostream&, const T&) or
		// operator<<(std::basic_stream<Char, CharTraits>, const Foo&) is more
		// specific.
		template <typename Char, typename CharTraits, typename T>
		::std::basic_ostream<Char, CharTraits> &operator<<(
		    ::std::basic_ostream<Char, CharTraits> &os, const T &x)
		{
			TypeWithoutFormatter < T,
			                     (internal::IsAProtocolMessage<T>::value ? kProtobuf :
			                      internal::ImplicitlyConvertible<const T &, internal::BiggestInt>::value ?
			                      kConvertibleToInteger : kOtherType) >::PrintValue(x, &os);
			return os;
		}

	}  // namespace internal2
}  // namespace testing

// This namespace MUST NOT BE NESTED IN ::testing, or the name look-up
// magic needed for implementing UniversalPrinter won't work.
namespace testing_internal
{

	// Used to print a value that is not an STL-style container when the
	// user doesn't define PrintTo() for it.
	template <typename T>
	void DefaultPrintNonContainerTo(const T &value, ::std::ostream *os)
	{
		// With the following statement, during unqualified name lookup,
		// testing::internal2::operator<< appears as if it was declared in
		// the nearest enclosing namespace that contains both
		// ::testing_internal and ::testing::internal2, i.e. the global
		// namespace.  For more details, refer to the C++ Standard section
		// 7.3.4-1 [namespace.udir].  This allows us to fall back onto
		// testing::internal2::operator<< in case T doesn't come with a <<
		// operator.
		//
		// We cannot write 'using ::testing::internal2::operator<<;', which
		// gcc 3.3 fails to compile due to a compiler bug.
		using namespace ::testing::internal2;  // NOLINT

		// Assuming T is defined in namespace foo, in the next statement,
		// the compiler will consider all of:
		//
		//   1. foo::operator<< (thanks to Koenig look-up),
		//   2. ::operator<< (as the current namespace is enclosed in ::),
		//   3. testing::internal2::operator<< (thanks to the using statement above).
		//
		// The operator<< whose type matches T best will be picked.
		//
		// We deliberately allow #2 to be a candidate, as sometimes it's
		// impossible to define #1 (e.g. when foo is ::std, defining
		// anything in it is undefined behavior unless you are a compiler
		// vendor.).
		*os << value;
	}

}  // namespace testing_internal

namespace testing
{
	namespace internal
	{

		// UniversalPrinter<T>::Print(value, ostream_ptr) prints the given
		// value to the given ostream.  The caller must ensure that
		// 'ostream_ptr' is not NULL, or the behavior is undefined.
		//
		// We define UniversalPrinter as a class template (as opposed to a
		// function template), as we need to partially specialize it for
		// reference types, which cannot be done with function templates.
		template <typename T>
		class UniversalPrinter;

		template <typename T>
		void UniversalPrint(const T &value, ::std::ostream *os);

		// Used to print an STL-style container when the user doesn't define
		// a PrintTo() for it.
		template <typename C>
		void DefaultPrintTo(IsContainer /* dummy */,
		                    false_type /* is not a pointer */,
		                    const C &container, ::std::ostream *os)
		{
			const size_t kMaxCount = 32;  // The maximum number of elements to print.
			*os << '{';
			size_t count = 0;
			for (typename C::const_iterator it = container.begin();
			     it != container.end(); ++it, ++count)
			{
				if (count > 0)
				{
					*os << ',';
					if (count == kMaxCount)    // Enough has been printed.
					{
						*os << " ...";
						break;
					}
				}
				*os << ' ';
				// We cannot call PrintTo(*it, os) here as PrintTo() doesn't
				// handle *it being a native array.
				internal::UniversalPrint(*it, os);
			}

			if (count > 0)
			{
				*os << ' ';
			}
			*os << '}';
		}

		// Used to print a pointer that is neither a char pointer nor a member
		// pointer, when the user doesn't define PrintTo() for it.  (A member
		// variable pointer or member function pointer doesn't really point to
		// a location in the address space.  Their representation is
		// implementation-defined.  Therefore they will be printed as raw
		// bytes.)
		template <typename T>
		void DefaultPrintTo(IsNotContainer /* dummy */,
		                    true_type /* is a pointer */,
		                    T *p, ::std::ostream *os)
		{
			if (p == NULL)
			{
				*os << "NULL";
			}
			else
			{
				// C++ doesn't allow casting from a function pointer to any object
				// pointer.
				//
				// IsTrue() silences warnings: "Condition is always true",
				// "unreachable code".
				if (IsTrue(ImplicitlyConvertible<T *, const void *>::value))
				{
					// T is not a function type.  We just call << to print p,
					// relying on ADL to pick up user-defined << for their pointer
					// types, if any.
					*os << p;
				}
				else
				{
					// T is a function type, so '*os << p' doesn't do what we want
					// (it just prints p as bool).  We want to print p as a const
					// void*.  However, we cannot cast it to const void* directly,
					// even using reinterpret_cast, as earlier versions of gcc
					// (e.g. 3.4.5) cannot compile the cast when p is a function
					// pointer.  Casting to UInt64 first solves the problem.
					*os << reinterpret_cast<const void *>(
					        reinterpret_cast<internal::UInt64>(p));
				}
			}
		}

		// Used to print a non-container, non-pointer value when the user
		// doesn't define PrintTo() for it.
		template <typename T>
		void DefaultPrintTo(IsNotContainer /* dummy */,
		                    false_type /* is not a pointer */,
		                    const T &value, ::std::ostream *os)
		{
			::testing_internal::DefaultPrintNonContainerTo(value, os);
		}

		// Prints the given value using the << operator if it has one;
		// otherwise prints the bytes in it.  This is what
		// UniversalPrinter<T>::Print() does when PrintTo() is not specialized
		// or overloaded for type T.
		//
		// A user can override this behavior for a class type Foo by defining
		// an overload of PrintTo() in the namespace where Foo is defined.  We
		// give the user this option as sometimes defining a << operator for
		// Foo is not desirable (e.g. the coding style may prevent doing it,
		// or there is already a << operator but it doesn't do what the user
		// wants).
		template <typename T>
		void PrintTo(const T &value, ::std::ostream *os)
		{
			// DefaultPrintTo() is overloaded.  The type of its first two
			// arguments determine which version will be picked.  If T is an
			// STL-style container, the version for container will be called; if
			// T is a pointer, the pointer version will be called; otherwise the
			// generic version will be called.
			//
			// Note that we check for container types here, prior to we check
			// for protocol message types in our operator<<.  The rationale is:
			//
			// For protocol messages, we want to give people a chance to
			// override Google Mock's format by defining a PrintTo() or
			// operator<<.  For STL containers, other formats can be
			// incompatible with Google Mock's format for the container
			// elements; therefore we check for container types here to ensure
			// that our format is used.
			//
			// The second argument of DefaultPrintTo() is needed to bypass a bug
			// in Symbian's C++ compiler that prevents it from picking the right
			// overload between:
			//
			//   PrintTo(const T& x, ...);
			//   PrintTo(T* x, ...);
			DefaultPrintTo(IsContainerTest<T>(0), is_pointer<T>(), value, os);
		}

		// The following list of PrintTo() overloads tells
		// UniversalPrinter<T>::Print() how to print standard types (built-in
		// types, strings, plain arrays, and pointers).

		// Overloads for various char types.
		GTEST_API_ void PrintTo(unsigned char c, ::std::ostream *os);
		GTEST_API_ void PrintTo(signed char c, ::std::ostream *os);
		inline void PrintTo(char c, ::std::ostream *os)
		{
			// When printing a plain char, we always treat it as unsigned.  This
			// way, the output won't be affected by whether the compiler thinks
			// char is signed or not.
			PrintTo(static_cast<unsigned char>(c), os);
		}

		// Overloads for other simple built-in types.
		inline void PrintTo(bool x, ::std::ostream *os)
		{
			*os << (x ? "true" : "false");
		}

		// Overload for wchar_t type.
		// Prints a wchar_t as a symbol if it is printable or as its internal
		// code otherwise and also as its decimal code (except for L'\0').
		// The L'\0' char is printed as "L'\\0'". The decimal code is printed
		// as signed integer when wchar_t is implemented by the compiler
		// as a signed type and is printed as an unsigned integer when wchar_t
		// is implemented as an unsigned type.
		GTEST_API_ void PrintTo(wchar_t wc, ::std::ostream *os);

		// Overloads for C strings.
		GTEST_API_ void PrintTo(const char *s, ::std::ostream *os);
		inline void PrintTo(char *s, ::std::ostream *os)
		{
			PrintTo(ImplicitCast_<const char *>(s), os);
		}

		// signed/unsigned char is often used for representing binary data, so
		// we print pointers to it as void* to be safe.
		inline void PrintTo(const signed char *s, ::std::ostream *os)
		{
			PrintTo(ImplicitCast_<const void *>(s), os);
		}
		inline void PrintTo(signed char *s, ::std::ostream *os)
		{
			PrintTo(ImplicitCast_<const void *>(s), os);
		}
		inline void PrintTo(const unsigned char *s, ::std::ostream *os)
		{
			PrintTo(ImplicitCast_<const void *>(s), os);
		}
		inline void PrintTo(unsigned char *s, ::std::ostream *os)
		{
			PrintTo(ImplicitCast_<const void *>(s), os);
		}

		// MSVC can be configured to define wchar_t as a typedef of unsigned
		// short.  It defines _NATIVE_WCHAR_T_DEFINED when wchar_t is a native
		// type.  When wchar_t is a typedef, defining an overload for const
		// wchar_t* would cause unsigned short* be printed as a wide string,
		// possibly causing invalid memory accesses.
#if !defined(_MSC_VER) || defined(_NATIVE_WCHAR_T_DEFINED)
		// Overloads for wide C strings
		GTEST_API_ void PrintTo(const wchar_t *s, ::std::ostream *os);
		inline void PrintTo(wchar_t *s, ::std::ostream *os)
		{
			PrintTo(ImplicitCast_<const wchar_t *>(s), os);
		}
#endif

		// Overload for C arrays.  Multi-dimensional arrays are printed
		// properly.

		// Prints the given number of elements in an array, without printing
		// the curly braces.
		template <typename T>
		void PrintRawArrayTo(const T a[], size_t count, ::std::ostream *os)
		{
			UniversalPrint(a[0], os);
			for (size_t i = 1; i != count; i++)
			{
				*os << ", ";
				UniversalPrint(a[i], os);
			}
		}

		// Overloads for ::string and ::std::string.
#if GTEST_HAS_GLOBAL_STRING
		GTEST_API_ void PrintStringTo(const ::string &s, ::std::ostream *os);
		inline void PrintTo(const ::string &s, ::std::ostream *os)
		{
			PrintStringTo(s, os);
		}
#endif  // GTEST_HAS_GLOBAL_STRING

		GTEST_API_ void PrintStringTo(const ::std::string &s, ::std::ostream *os);
		inline void PrintTo(const ::std::string &s, ::std::ostream *os)
		{
			PrintStringTo(s, os);
		}

		// Overloads for ::wstring and ::std::wstring.
#if GTEST_HAS_GLOBAL_WSTRING
		GTEST_API_ void PrintWideStringTo(const ::wstring &s, ::std::ostream *os);
		inline void PrintTo(const ::wstring &s, ::std::ostream *os)
		{
			PrintWideStringTo(s, os);
		}
#endif  // GTEST_HAS_GLOBAL_WSTRING

#if GTEST_HAS_STD_WSTRING
		GTEST_API_ void PrintWideStringTo(const ::std::wstring &s, ::std::ostream *os);
		inline void PrintTo(const ::std::wstring &s, ::std::ostream *os)
		{
			PrintWideStringTo(s, os);
		}
#endif  // GTEST_HAS_STD_WSTRING

#if GTEST_HAS_TR1_TUPLE
		// Overload for ::std::tr1::tuple.  Needed for printing function arguments,
		// which are packed as tuples.

		// Helper function for printing a tuple.  T must be instantiated with
		// a tuple type.
		template <typename T>
		void PrintTupleTo(const T &t, ::std::ostream *os);

		// Overloaded PrintTo() for tuples of various arities.  We support
		// tuples of up-to 10 fields.  The following implementation works
		// regardless of whether tr1::tuple is implemented using the
		// non-standard variadic template feature or not.

		inline void PrintTo(const ::std::tr1::tuple<> &t, ::std::ostream *os)
		{
			PrintTupleTo(t, os);
		}

		template <typename T1>
		void PrintTo(const ::std::tr1::tuple<T1> &t, ::std::ostream *os)
		{
			PrintTupleTo(t, os);
		}

		template <typename T1, typename T2>
		void PrintTo(const ::std::tr1::tuple<T1, T2> &t, ::std::ostream *os)
		{
			PrintTupleTo(t, os);
		}

		template <typename T1, typename T2, typename T3>
		void PrintTo(const ::std::tr1::tuple<T1, T2, T3> &t, ::std::ostream *os)
		{
			PrintTupleTo(t, os);
		}

		template <typename T1, typename T2, typename T3, typename T4>
		void PrintTo(const ::std::tr1::tuple<T1, T2, T3, T4> &t, ::std::ostream *os)
		{
			PrintTupleTo(t, os);
		}

		template <typename T1, typename T2, typename T3, typename T4, typename T5>
		void PrintTo(const ::std::tr1::tuple<T1, T2, T3, T4, T5> &t,
		             ::std::ostream *os)
		{
			PrintTupleTo(t, os);
		}

		template <typename T1, typename T2, typename T3, typename T4, typename T5,
		          typename T6>
		void PrintTo(const ::std::tr1::tuple<T1, T2, T3, T4, T5, T6> &t,
		             ::std::ostream *os)
		{
			PrintTupleTo(t, os);
		}

		template <typename T1, typename T2, typename T3, typename T4, typename T5,
		          typename T6, typename T7>
		void PrintTo(const ::std::tr1::tuple<T1, T2, T3, T4, T5, T6, T7> &t,
		             ::std::ostream *os)
		{
			PrintTupleTo(t, os);
		}

		template <typename T1, typename T2, typename T3, typename T4, typename T5,
		          typename T6, typename T7, typename T8>
		void PrintTo(const ::std::tr1::tuple<T1, T2, T3, T4, T5, T6, T7, T8> &t,
		             ::std::ostream *os)
		{
			PrintTupleTo(t, os);
		}

		template <typename T1, typename T2, typename T3, typename T4, typename T5,
		          typename T6, typename T7, typename T8, typename T9>
		void PrintTo(const ::std::tr1::tuple<T1, T2, T3, T4, T5, T6, T7, T8, T9> &t,
		             ::std::ostream *os)
		{
			PrintTupleTo(t, os);
		}

		template <typename T1, typename T2, typename T3, typename T4, typename T5,
		          typename T6, typename T7, typename T8, typename T9, typename T10>
		void PrintTo(
		    const ::std::tr1::tuple<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10> &t,
		    ::std::ostream *os)
		{
			PrintTupleTo(t, os);
		}
#endif  // GTEST_HAS_TR1_TUPLE

		// Overload for std::pair.
		template <typename T1, typename T2>
		void PrintTo(const ::std::pair<T1, T2> &value, ::std::ostream *os)
		{
			*os << '(';
			// We cannot use UniversalPrint(value.first, os) here, as T1 may be
			// a reference type.  The same for printing value.second.
			UniversalPrinter<T1>::Print(value.first, os);
			*os << ", ";
			UniversalPrinter<T2>::Print(value.second, os);
			*os << ')';
		}

		// Implements printing a non-reference type T by letting the compiler
		// pick the right overload of PrintTo() for T.
		template <typename T>
		class UniversalPrinter
		{
		public:
			// MSVC warns about adding const to a function type, so we want to
			// disable the warning.
#ifdef _MSC_VER
# pragma warning(push)          // Saves the current warning state.
# pragma warning(disable:4180)  // Temporarily disables warning 4180.
#endif  // _MSC_VER

			// Note: we deliberately don't call this PrintTo(), as that name
			// conflicts with ::testing::internal::PrintTo in the body of the
			// function.
			static void Print(const T &value, ::std::ostream *os)
			{
				// By default, ::testing::internal::PrintTo() is used for printing
				// the value.
				//
				// Thanks to Koenig look-up, if T is a class and has its own
				// PrintTo() function defined in its namespace, that function will
				// be visible here.  Since it is more specific than the generic ones
				// in ::testing::internal, it will be picked by the compiler in the
				// following statement - exactly what we want.
				PrintTo(value, os);
			}

#ifdef _MSC_VER
# pragma warning(pop)           // Restores the warning state.
#endif  // _MSC_VER
		};

		// UniversalPrintArray(begin, len, os) prints an array of 'len'
		// elements, starting at address 'begin'.
		template <typename T>
		void UniversalPrintArray(const T *begin, size_t len, ::std::ostream *os)
		{
			if (len == 0)
			{
				*os << "{}";
			}
			else
			{
				*os << "{ ";
				const size_t kThreshold = 18;
				const size_t kChunkSize = 8;
				// If the array has more than kThreshold elements, we'll have to
				// omit some details by printing only the first and the last
				// kChunkSize elements.
				// TODO(wan@google.com): let the user control the threshold using a flag.
				if (len <= kThreshold)
				{
					PrintRawArrayTo(begin, len, os);
				}
				else
				{
					PrintRawArrayTo(begin, kChunkSize, os);
					*os << ", ..., ";
					PrintRawArrayTo(begin + len - kChunkSize, kChunkSize, os);
				}
				*os << " }";
			}
		}
		// This overload prints a (const) char array compactly.
		GTEST_API_ void UniversalPrintArray(
		    const char *begin, size_t len, ::std::ostream *os);

		// This overload prints a (const) wchar_t array compactly.
		GTEST_API_ void UniversalPrintArray(
		    const wchar_t *begin, size_t len, ::std::ostream *os);

		// Implements printing an array type T[N].
		template <typename T, size_t N>
		class UniversalPrinter<T[N]>
		{
		public:
			// Prints the given array, omitting some elements when there are too
			// many.
			static void Print(const T(&a)[N], ::std::ostream *os)
			{
				UniversalPrintArray(a, N, os);
			}
		};

		// Implements printing a reference type T&.
		template <typename T>
		class UniversalPrinter<T &>
		{
		public:
			// MSVC warns about adding const to a function type, so we want to
			// disable the warning.
#ifdef _MSC_VER
# pragma warning(push)          // Saves the current warning state.
# pragma warning(disable:4180)  // Temporarily disables warning 4180.
#endif  // _MSC_VER

			static void Print(const T &value, ::std::ostream *os)
			{
				// Prints the address of the value.  We use reinterpret_cast here
				// as static_cast doesn't compile when T is a function type.
				*os << "@" << reinterpret_cast<const void *>(&value) << " ";

				// Then prints the value itself.
				UniversalPrint(value, os);
			}

#ifdef _MSC_VER
# pragma warning(pop)           // Restores the warning state.
#endif  // _MSC_VER
		};

		// Prints a value tersely: for a reference type, the referenced value
		// (but not the address) is printed; for a (const) char pointer, the
		// NUL-terminated string (but not the pointer) is printed.

		template <typename T>
		class UniversalTersePrinter
		{
		public:
			static void Print(const T &value, ::std::ostream *os)
			{
				UniversalPrint(value, os);
			}
		};
		template <typename T>
		class UniversalTersePrinter<T &>
		{
		public:
			static void Print(const T &value, ::std::ostream *os)
			{
				UniversalPrint(value, os);
			}
		};
		template <typename T, size_t N>
		class UniversalTersePrinter<T[N]>
		{
		public:
			static void Print(const T(&value)[N], ::std::ostream *os)
			{
				UniversalPrinter<T[N]>::Print(value, os);
			}
		};
		template <>
		class UniversalTersePrinter<const char *>
		{
		public:
			static void Print(const char *str, ::std::ostream *os)
			{
				if (str == NULL)
				{
					*os << "NULL";
				}
				else
				{
					UniversalPrint(string(str), os);
				}
			}
		};
		template <>
		class UniversalTersePrinter<char *>
		{
		public:
			static void Print(char *str, ::std::ostream *os)
			{
				UniversalTersePrinter<const char *>::Print(str, os);
			}
		};

#if GTEST_HAS_STD_WSTRING
		template <>
		class UniversalTersePrinter<const wchar_t *>
		{
		public:
			static void Print(const wchar_t *str, ::std::ostream *os)
			{
				if (str == NULL)
				{
					*os << "NULL";
				}
				else
				{
					UniversalPrint(::std::wstring(str), os);
				}
			}
		};
#endif

		template <>
		class UniversalTersePrinter<wchar_t *>
		{
		public:
			static void Print(wchar_t *str, ::std::ostream *os)
			{
				UniversalTersePrinter<const wchar_t *>::Print(str, os);
			}
		};

		template <typename T>
		void UniversalTersePrint(const T &value, ::std::ostream *os)
		{
			UniversalTersePrinter<T>::Print(value, os);
		}

		// Prints a value using the type inferred by the compiler.  The
		// difference between this and UniversalTersePrint() is that for a
		// (const) char pointer, this prints both the pointer and the
		// NUL-terminated string.
		template <typename T>
		void UniversalPrint(const T &value, ::std::ostream *os)
		{
			// A workarond for the bug in VC++ 7.1 that prevents us from instantiating
			// UniversalPrinter with T directly.
			typedef T T1;
			UniversalPrinter<T1>::Print(value, os);
		}

#if GTEST_HAS_TR1_TUPLE
		typedef ::std::vector<string> Strings;

		// This helper template allows PrintTo() for tuples and
		// UniversalTersePrintTupleFieldsToStrings() to be defined by
		// induction on the number of tuple fields.  The idea is that
		// TuplePrefixPrinter<N>::PrintPrefixTo(t, os) prints the first N
		// fields in tuple t, and can be defined in terms of
		// TuplePrefixPrinter<N - 1>.

		// The inductive case.
		template <size_t N>
		struct TuplePrefixPrinter
		{
			// Prints the first N fields of a tuple.
			template <typename Tuple>
			static void PrintPrefixTo(const Tuple &t, ::std::ostream *os)
			{
				TuplePrefixPrinter < N - 1 >::PrintPrefixTo(t, os);
				*os << ", ";
				UniversalPrinter < typename ::std::tr1::tuple_element < N - 1, Tuple >::type >
				::Print(::std::tr1::get < N - 1 > (t), os);
			}

			// Tersely prints the first N fields of a tuple to a string vector,
			// one element for each field.
			template <typename Tuple>
			static void TersePrintPrefixToStrings(const Tuple &t, Strings *strings)
			{
				TuplePrefixPrinter < N - 1 >::TersePrintPrefixToStrings(t, strings);
				::std::stringstream ss;
				UniversalTersePrint(::std::tr1::get < N - 1 > (t), &ss);
				strings->push_back(ss.str());
			}
		};

		// Base cases.
		template <>
		struct TuplePrefixPrinter<0>
		{
			template <typename Tuple>
			static void PrintPrefixTo(const Tuple &, ::std::ostream *) {}

			template <typename Tuple>
			static void TersePrintPrefixToStrings(const Tuple &, Strings *) {}
		};
		// We have to specialize the entire TuplePrefixPrinter<> class
		// template here, even though the definition of
		// TersePrintPrefixToStrings() is the same as the generic version, as
		// Embarcadero (formerly CodeGear, formerly Borland) C++ doesn't
		// support specializing a method template of a class template.
		template <>
		struct TuplePrefixPrinter<1>
		{
			template <typename Tuple>
			static void PrintPrefixTo(const Tuple &t, ::std::ostream *os)
			{
				UniversalPrinter<typename ::std::tr1::tuple_element<0, Tuple>::type>::
				Print(::std::tr1::get<0>(t), os);
			}

			template <typename Tuple>
			static void TersePrintPrefixToStrings(const Tuple &t, Strings *strings)
			{
				::std::stringstream ss;
				UniversalTersePrint(::std::tr1::get<0>(t), &ss);
				strings->push_back(ss.str());
			}
		};

		// Helper function for printing a tuple.  T must be instantiated with
		// a tuple type.
		template <typename T>
		void PrintTupleTo(const T &t, ::std::ostream *os)
		{
			*os << "(";
			TuplePrefixPrinter<::std::tr1::tuple_size<T>::value>::
			PrintPrefixTo(t, os);
			*os << ")";
		}

		// Prints the fields of a tuple tersely to a string vector, one
		// element for each field.  See the comment before
		// UniversalTersePrint() for how we define "tersely".
		template <typename Tuple>
		Strings UniversalTersePrintTupleFieldsToStrings(const Tuple &value)
		{
			Strings result;
			TuplePrefixPrinter<::std::tr1::tuple_size<Tuple>::value>::
			TersePrintPrefixToStrings(value, &result);
			return result;
		}
#endif  // GTEST_HAS_TR1_TUPLE

	}  // namespace internal

	template <typename T>
	::std::string PrintToString(const T &value)
	{
		::std::stringstream ss;
		internal::UniversalTersePrinter<T>::Print(value, &ss);
		return ss.str();
	}

}  // namespace testing

#endif  // GTEST_INCLUDE_GTEST_GTEST_PRINTERS_H_
